Changes

Change normalization of sensitivity matrix.
Before it was normalized by (default-observed) values of metrics.
Now it is normalized by 1/obs.  This leaves the sensitivity matrix
free from dependence on the bias and puts the bias entirely
on the right-hand side of the matrix equation.
Also, the parameter values are no longer normalized by max(def,sens)
values.  Instead, they are normalized by the values used
in the default simulation, and a sensitivity simulation value
is used only if the default-simulation value is zero.

Add plots of left-singular vectors and right-singular vectors.
Annotate these plots with singular values.

One of the unit tests, test_3x2_C8transformed, is broken.

For #910.